Vacuum still



May 29, 1951 K. C. D. HICKMAN VACUUM STILL Filed March 21, 1946 T0maul/M F1 1 f0 VACUUM PUMPS PUMPJ 2 48 34 3; HL ATERs F6\M/wvvwwwwwvwwvwm/wOvwwwMA/wm/vwmA/ww 9 *5AMANWVWWMNMMMWVWMMMMNWMMMAMNW] LD/ST/LLAND IN 34 4 \HEATERJ 38 I 44D/577LLATE 4 24 our D/577LLATE our FIG Z.

o o 34 0 I H54TER$ 0 o REFLECTOR IENNETH. C.D.HIC

INVENTOR 33 ATTORNEY Patented May 29, 1951 VACUUM STILL Kenneth C. D.Hickman, Rochester, N. Y., as-

signor, by mesne assignments, to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Application March 21, 1946; Serial No.656,114

3 Claims.

This invention relates to improvements in vacuum distillation'apparatus,particularly of the type wherein high vacuum exists between thevaporizing and condensing surfaces.

It is known to distill decomposable substances under vacuum conditionssuch that a relatively high Vacuum exists between the vaporizing andcondensing surfaces. This is accomplished by having a relativelyunobstructed space for the flow of vapors from the vaporizing to thecondensing surface. In constructions heretofore used, this hasnecessitated the placing of the condensing surface opposite the heatedvaporizing surface which resulted in considerable loss of heat from thehot vaporizing surface to the cold condensing surface. Also, it is usualpractice in this art to form the distilland into a thin film, supportedby a heated vaporizing surface. Since the vaporization takes place onlyfrom the surface of the film opposite from the supporting heatedsurface, the heat of vaporization reached the actual point ofvaporization only by passage through the film of distilland. The portionof this film adjacent the vaporizing surface was, therefore, overheatedin order to deliver sufficient heat to the portion of the filmundergoing vaporization. This results in enhanced thermal decompositionin the layer next to the support.

This invention has for its object to overcome the above difficulties.Another object is to provide improved vacuum distillation apparatus inwhich the loss of heat is reduced to an important extent. Another objectis to provide improved vacuum distillation apparatus which will reducethe thermal gradient in the film of distilland while it is undergoingdistillation. A still further object is to reduce the thermal gradientin the distilling film. Other objects will appear hereinafter.

These and other objects are accomplished by my invention which includesa vacuum still having a rotatable approximately cylindrical vaporizingsurface with a condensing surface positioned at an open end thereof.

In the following description I have given certain preferred embodimentsof my invention but it is to be understood these are set forth by way ofillustration and not in limitation thereof.

In the accompanying drawings, Fig. 1 is a vertical section of animproved vacuum still embodying the features of my invention and Fig. 2is a vertical section taken at right angles to Fig. l and on line 2-2 ofFig. 1.

Referring to'the drawings, numeral 4 designates a cylindrical shellclosed at one end by an integral plate 6 and at the opposite end by aremovable plate 8 which makes a gas-tight connection with shell 4 bymeans of a gasket ii) placed between the bolted flanges 22 and I4.Numeral l6 designates a shaft positioned centrally within cylindricalshell 4 and rotatably mounted in bearings l8 and 20. Bearing 2B isprovided with a suitable gas-tight packed gland 22. The shaft is rotatedby power applied to pulley 24. Numeral 26 designates a cylindricalvaporizing surface mounted upon shaft 29 and concentric therewith.Numeral 2? designates supporting members which maintain the cylindricalvaporizing surface 26 in the position shown and which are integral withshaft It. The ends of cylinder 26 are turned inwardly as indicated bythe numerals 28 and 30. I

vaporizing cylinder 26 is surrounded by a plurality of heating elements32 and by a cylindrical reflector 34 which is preferably highly polishedon the inside surface to reflect heat from elements 32 onto the outsideof cylinder 26. Numeral 36 designates a conduit for introducingdistilland onto the inside surface of vaporizing cylinder 26 and numeral38 designates a conduit for removing undistilled residue accumulating atthe end of vaporizing cylinder 26.

The cylindrical shell 4 is provided with an annular collar All and 42 ateach end thereof. These annular collars serve in conjunction with theend plates 6 and 8 to form gutters at each end of the shell in whichdistilland is collected. Numerals 44 and 46 designate conduits throughwhich liquid is withdrawn from these gutters. Numeral 48 designatesconduits to which are connected backing pumps (not shown) for evacuatingthe still shell. 1

In operating the apparatus, material to be distilled is introducedthrough conduit 36 onto the inside surface of vaporizing cylinder 25.Shell d is evacuated and shaft it is caused to rotate by force appliedto pulley 24 and electric heating elements 32 are actuated to heatsurface 26 to distilling temperature. The distilland is caused to flowby centrifugal force in a thin film over the inside surface of cylinder25. This film is heated to distillation temperature and the vapors whichare generated pass toward the ends of the cylinder 26. Since the lowestboiling components would be vaporized first they would pass outwardlythrough the left hand end of cylinder 26 and would condense on the aircooled end plate 6. The condensate would run to the bottom of the gutterformed by collar to and would be with-- drawn through conduit 44. Thehigher boiling portions of the distilland would be vaporized toward theright hand end of the cylinder 26 and would pass through the right handend and into contact with air cooled end plate 8 where they would becondensed, flow to the bottom of the gutter, formed by collar 42, andwould be withdrawn as a high boiling fraction through conduit 46.Undistilled residue would be forced into the end of conduit 38 by thedirection of rotation, as indicated in Fig. 2 and this undistilledresidue would be withdrawn from the still in this manner. Reflector 34serves to concentrate the heat on the vaporizing surface 26.

Instead of introducing the distilland at one end of the vaporizingcylinder 26 and thus separating two fractions, it would be advisable insome cases to introduce it at other points in the cylinder, in whichcase there would not be as great a difference in the distillingtemperature of the fractions obtained orthey would be identical ifintroduction took place at the middle of the cylinder.

Since the vaporizing surface is cylindrical and there is no opposingcondensing surface, the loss of heat is materially reduced, At the sametime substantially unobstructed space for the flow oi vapors to thecondensing surface is provided. Each unit of the vaporizing surface isopposite another heated unit of the vaporizing surface so that anyradiation of heat which does take place is utilized by the opposite unitof the vaporizing surface. This heat is applied at the outside of thedistilling film and this avoids the necessity of introducing excess heatto the portion of the film adjacent the heated support, as in priorconstructions. Ihe thermal gradient through the distilling film and itsattendant thermal. decomposition is thus reduced.

What I claim is:

1. Vacuum distillation apparatus comprising a gas-tight chamber having ahorizontally disposed cylindrical side wall and vertically disposed endwalls, evacuating means for said chamber, an open-ended cylindricalevaporating member disposed horizontally in said chamber and generallyconcentrically therewith, the ends of said evaporating member'beingspaced from the end walls of said chamber and being turned inwardly toprovide a peripheral lip at each end of said evaporating member, arotatable shaft extending'axially through said evaporating member andcarrying said evaporating member for rotation therewith, means forrotating said shaft, a cylindrical heatrefiecting member positionedaround substantially the extent of said evaporating member and generallyconcentric therewith, radiant heating means disposed about saidevaporating member between said evaporating member and saidheatrefiecting member, conduit means arranged to introduce material tobe distilled onto the inner surface of said evaporating member,secondary conduit means spaced from said first-named condui't means andarranged to withdraw undistilled residue from the inner surface of saidevaporating member, projecting members extending inwardly from said sidewall adjacent each said end wall of saidchamberand forming with said endwalls gutters for collecting distillate condensing on said end walls,and conduit means arranged for withdrawing distillate from said gutters.

2. Vacuum distillation apparatus comprising generally horizontallydisposed cylindrical side wall means and generally vertical end wallmeans forming a gas-tight chamber, evacuating means for said chamber, anopen-ended vaporizing cylinder rotatably mounted in said chamber andgenerally concentric therewith, the ends of said cylinder being spacedfrom said end wall means, means for rotating said cylinder, heatingmeans positioned around said vaporizing cylinder and arranged to heatsaid vaporizing cylinder to distilling temperature, said heating meansbeing spaced from said end wall means and out of heating relationtherewith, whereby said end wall means form condensing surface means fordistilling vapors issuing from said vaporizing cylinder, conduit meansarranged to introduce material to be distilled onto the inner surface ofsaid vaporizing cylinder, secondary conduit means spaced from saidfirst-named conduit means and arranged to withdraw undistilled residuefrom said vaporizing cylinder, gutter means arranged to collectcondensate from said end wall means, and conduit means for withdrawingcondensate from said gutter means.

3. Vacuum distillation apparatus comprising wall means forming agas-tight chamber, means for evacuating said chamber, a generallyhorizontally disposed open-ended vaporizing cylinder rotatably mountedin said chamber, the interior of said cylinder being substantiallyunobstructed, the ends of said cylinder being spaced from said wallmeans, means for rotating said cylinder, a heat reflector positionedabout substantially the extent of said vaporizing cylinder, heatingmeans disposed between said heat reflector and said vaporizing cylinder,means for introducing distilland on. the inner surface of saidvaporizing cylinder, means spaced from said last-named means forremoving undistilled residue from the inner surface of said vaporizingcylinder, and gutter means arranged to collect condensate condensing onsaid wall means.

KENNETH C. D. HICKMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 27,503 Willard Mar. 13, 1860440,752 Borotte Nov. .18, 1890 552,456 'Theisen Dec. 31, 1895 1,286,315Heuser Dec. 3, 1918 2,220,171 Woaillon Nov. 5, 1940 2,224,621 VoorheesDec. 10, 1940 2,234,166 Hickman Mar. 11, 1941 2,385,074 Guignard Sept.18, 1945 2,427,718 Denys Sept. 23, 1947 2,437,594 Denys 1 Mar. 9, 1948FOREIGN PATENTS Number Country Date 11,350 Great Britain of 1889

